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llvm-mirror/test/Transforms/AddDiscriminators/memcpy-discriminator.ll
Shiva Chen a2029fa58e [DebugInfo] Add DILabel metadata and intrinsic llvm.dbg.label.
In order to set breakpoints on labels and list source code around
labels, we need collect debug information for labels, i.e., label
name, the function label belong, line number in the file, and the
address label located. In order to keep these information in LLVM
IR and to allow backend to generate debug information correctly.
We create a new kind of metadata for labels, DILabel. The format
of DILabel is

!DILabel(scope: !1, name: "foo", file: !2, line: 3)

We hope to keep debug information as much as possible even the
code is optimized. So, we create a new kind of intrinsic for label
metadata to avoid the metadata is eliminated with basic block.
The intrinsic will keep existing if we keep it from optimized out.
The format of the intrinsic is

llvm.dbg.label(metadata !1)

It has only one argument, that is the DILabel metadata. The
intrinsic will follow the label immediately. Backend could get the
label metadata through the intrinsic's parameter.

We also create DIBuilder API for labels to be used by Frontend.
Frontend could use createLabel() to allocate DILabel objects, and use
insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR.

Differential Revision: https://reviews.llvm.org/D45024

Patch by Hsiangkai Wang.

llvm-svn: 331841
2018-05-09 02:40:45 +00:00

105 lines
3.9 KiB
LLVM

; RUN: opt < %s -add-discriminators -sroa -S | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
; Test case obtained from the following C code:
; struct A {
; int field1;
; short field2;
; };
;
; struct B {
; struct A field1;
; int field2;
; };
;
;
; extern struct B g_b;
; extern int bar(struct B b, int c);
;
; int foo(int cond) {
; int result = cond ? bar(g_b, 33) : 42;
; return result;
; }
; In this test, global variable g_b is passed by copy to function bar. That
; copy is located on the stack (see alloca %g_b.coerce), and it is initialized
; by a memcpy call.
;
; SROA would split alloca %g_b.coerce into two (smaller disjoint) slices:
; slice [0,8) and slice [8, 12). Users of the original alloca are rewritten
; as users of the new alloca slices.
; In particular, the memcpy is rewritten by SROA as two load/store pairs.
;
; Later on, mem2reg successfully promotes the new alloca slices to registers,
; and loads %3 and %5 are made redundant by the loads obtained from the memcpy
; intrinsic expansion.
;
; If pass AddDiscriminators doesn't assign a discriminator to the intrinsic
; memcpy call, then the loads obtained from the memcpy expansion would not have
; a correct discriminator.
;
; This test checks that the two new loads inserted by SROA in %cond.true
; correctly reference a debug location with a non-zero discriminator. This test
; also checks that the same discriminator is used by all instructions from
; basic block %cond.true.
%struct.B = type { %struct.A, i32 }
%struct.A = type { i32, i16 }
@g_b = external global %struct.B, align 4
define i32 @foo(i32 %cond) #0 !dbg !5 {
entry:
%g_b.coerce = alloca { i64, i32 }, align 4
%tobool = icmp ne i32 %cond, 0, !dbg !7
br i1 %tobool, label %cond.true, label %cond.end, !dbg !7
cond.true:
; CHECK-LABEL: cond.true:
; CHECK: load i64, {{.*}}, !dbg ![[LOC:[0-9]+]]
; CHECK-NEXT: load i32, {{.*}}, !dbg ![[LOC]]
; CHECK-NEXT: %call = call i32 @bar({{.*}}), !dbg ![[LOC]]
; CHECK-NEXT: br label %cond.end, !dbg ![[BR_LOC:[0-9]+]]
; CHECK-DAG: ![[LOC]] = !DILocation(line: 16, column: 23, scope: ![[SCOPE:[0-9]+]])
; CHECK-DAG: ![[SCOPE]] = !DILexicalBlockFile({{.*}}, discriminator: 2)
; CHECK-DAG: ![[BR_LOC]] = !DILocation(line: 16, column: 16, scope: ![[SCOPE]])
%0 = bitcast { i64, i32 }* %g_b.coerce to i8*, !dbg !8
%1 = bitcast %struct.B* @g_b to i8*, !dbg !8
call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 %0, i8* align 4 %1, i64 12, i1 false), !dbg !8
%2 = getelementptr inbounds { i64, i32 }, { i64, i32 }* %g_b.coerce, i32 0, i32 0, !dbg !8
%3 = load i64, i64* %2, align 4, !dbg !8
%4 = getelementptr inbounds { i64, i32 }, { i64, i32 }* %g_b.coerce, i32 0, i32 1, !dbg !8
%5 = load i32, i32* %4, align 4, !dbg !8
%call = call i32 @bar(i64 %3, i32 %5, i32 33), !dbg !8
br label %cond.end, !dbg !7
cond.end: ; preds = %entry, %cond.true
%cond1 = phi i32 [ %call, %cond.true ], [ 42, %entry ], !dbg !7
ret i32 %cond1, !dbg !9
}
declare i32 @bar(i64, i32, i32)
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i1) #1
attributes #0 = { noinline nounwind uwtable }
attributes #1 = { argmemonly nounwind }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2)
!1 = !DIFile(filename: "test.c", directory: ".")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 15, type: !6, isLocal: false, isDefinition: true, scopeLine: 15, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
!6 = !DISubroutineType(types: !2)
!7 = !DILocation(line: 16, column: 16, scope: !5)
!8 = !DILocation(line: 16, column: 23, scope: !5)
!9 = !DILocation(line: 17, column: 3, scope: !5)